Field
This disclosure relates to methods and systems for treatment of neurological disorders, and particularly for treating brain disorders using electrodes.
Description of the Related Art
Brain stimulation has been shown to be effective for the treatment of Parkinson's Disease and other movement disorders, Epilepsy, and Depression. Brain stimulation has the potential to be an effective treatment for numerous other disorders. Recently brain stimulation has been shown to be effective in enhancing memory when targeted at a component of the Papez circuit, a memory circuit of the brain, including the hippocampus, fornix, anterior thalamus etc. Clinical trials have been initiated to investigate fornix stimulation for Alzheimer's disease and its precursor, mild cognitive impairment (MCI). Furthermore, Lozano has also proposed stimulation of the anterior nucleus of the thalamus as another target for Alzheimer's disease and MCI.
Idiopathic Normal Pressure Hydrocephalus (NPH) is another neurological disorder that may be related to dementia, MCI, and Alzheimer's disease. NPH, however, is treated differently than the proposed treatment for MCI and Alzheimer's disease. The mainstay of treatment for NPH is the use of a ventricular shunt to divert cerebral spinal fluid (CSF) to the peritoneum, atrium, or pleural space. It is thought that the size of the ventricles in NPH is greater than the expected ventricular enlargement due to brain atrophy called hydrocephalus ex vacuo. By draining CSF, the size of the ventricles can be reduced and pressure on specific sensitive areas of the brain is thought to be reduced. NPH is typically associated with a triad of clinical symptoms, namely memory loss, gait instability, and urinary incontinence. Ventricular shunts have been shown to improve all three components of the clinical triad but are most successful and effective for gait and least effective for memory and cognitive changes. It has been proposed that NPH is an entity belonging to a spectrum of dementias. A recent study by Koivisto et al. (Poor Cognitive Outcome in Shunt-Responsive Idiopathic Normal Pressure Hydrocephalus. Neurosurgery 72(1):1-8 (2013)) demonstrated that while the diagnosis of NPH was not initially associated with dementia, a high number of patients with NPH that were treated with ventricular shunts later developed dementia including Alzheimer's disease. Given this association of NPH with dementia and Alzheimer's disease, it seems that the use of ventricular shunting for NPH is not effective in preventing the development of dementia and dementia related symptoms such as memory and cognitive decline in these patients.